Photoelectric facsimile transmitter



NOV. 25, 1941. i -rs 2,263,592 v PHOTOELECTRIC FAdsIMILE TRANSMITTERFiled March 13; 1939 6 Sheets-Sheet l INVENTOR. LOUIS M. PoTTs A ORNEY.

Nov. 25, 1941. I L. M. POTTS PHOTOELECTRIC FQCSIMILE TRANSMITTER FiledMarch 13, 1939 6 Sheets-Sheet 2 INVENTORY LOUIS M. POTTS Nov. 25, 1941,I P TT 2,263,592

PHOT OELEGTRIC FACSIMILE TRANSMITTER Filed March 13, '1959 6Sheets-Sheet :5

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Nov. 25, 1941. po 'rs 2,263,592

HOTOELECTRIC FACSIMILE TRANSMITTER Filed March 13, 1959 v 6 Sheets-Sheet4 FIG. l6

INVENT OR. LOUIS M. POTTS ATTORNE Nov 25, 1941. M. POTTS PHOTOELECTRICFACSIMILE TRANSMITTER FiledMarch 13, 1939 6 Sheets-Sheet 5 www INVENTOR.

LOUIS M. POTTS A ORNEY.

Nov. 25, 1941. POT-rs v 2,263,592

PHOTOELECTRIC FAGSIMILE TRANSMITTER Filed March 13, 1939 6 Sheets-Sheet6 INVENTOR. LOUIS M. POTTS A ORNEY.

Patented Nov. 25, 1941 PHOTOELECTRIC FACSIMILE TRAN SMITTER.

Louis M. Potts, Evanston, Ill., assignor to Teletype Corporation,Chicago, 11]., a corporation of Delaware Application March 13, 1939,Serial No. 261,418

54 Claims.

This invention pertains to transmitters and particularly to a facsimiletransmitter in which the transmission of facsimile signals is controlledthrough a photoelectric system.

In telegraph systems involving apparatus for recording characters by a,series of elemental areas of positive and negative surfaces,transmitting apparatus has been employed wherein each letter, symbol, orcharacter is scanned or analyzed into a succession of constituent areas.In

accordance with such scanned or analyzed areas,

electrical impulses are generated which cause corresponding operation ofrecording apparatus of the form disclosed in U. S. Patent No 2,000,-

083, issued May 7, 1935, to form the characters tion, there is provideda keyboard-controlled photoelectric transmitter for facsimile telegraphy which comprises a cylindrical screen having rows of apertures (oropaque and transparent portions) and rotatable within a cylindricalhousing having a longitudinal row of holes adapted to be uncovered bythe alignment of apertures in a plurality of permutationbars controlledby the keys so that a photoelectric cell is activated by a light sourceto transmit impulses.

More specifically, instead of providing in a facsimile transmitter, aplurality of transmitting discs wherein the periphery of each disc is socut that it corresponds to a different character to be transmitted, thepresent invention provides a scanning cylinder or screen having aplurality of circumferential rows of holes, in which each row isanalogous in function to a transmitting disc of the transmitter shown inthe aforementioned patent. The arrangement of the holes in eachcircumferential row corresponds to the manner in which the periphery ofthe corresponding disc in the disc-type transmitter is out. In thedisctype of transmitter, the scanning or sensing'of the disc isaccomplished by a contact lever individual to each disc, while in thephotoelectric transmitter .the sensing or scanning is accomaligned holesin a series of permutation bars onto a photoelectric cell rotated withinthe cylinder. In the disc-type, the scanning contact lever associatedwith each disc is selected by a series of permutation bars, theoccurrence of an alignment of notches permitting one arm of said leverto fall thereinto, thus causing said lever to rotate into contactualengagement with the disc. In the photoelectric transmitter, thepermutation bars comprise a series of thin plates arranged in laminatedmanner, the thin plates being provided with holes which, when aligned,permit a beam of light to be directed therethrough. Instead of havingcode notches on the edges, th( se permutation plates are each providedwith a row of holes corresponding to said notches, whereby for eachpermutative setting of the plate (by means of key levers or tapecontrolled levers) an alignment of holes will result opposite theselected circumferential row of holes in the scanning cylinder, throughwhich the beam of light is permitted to pass to impinge upon thephotoelectric cell. As the scanning cylinder makes one complete rotationa series of marking and spacing impulses corresponding to the particulararrangement of holes in the selected circumferential row is transmitted,under the control of the photoelectric cell, over the signal line orchannel to operate afacsimile printer.

Another feature of the invention consists in providing a keyboardtransmitter wherein the hole opposite the row of apertures to be sensedor scanned is uncovered by a shutter controlled by the keys of thekeyboard so that the photoelectric cell is activated by the beam oflight projected through the uncovered hole.

According to another feature of the invention light is conducted ortransmitted from a single concentrated source through a series of quartzrods extending from the scanning holes' opposite the circumferential rowof holes to be scanned to a photoelectric source.

A fuller understanding of the invention may be had from the followingdescription, taken in conjunction with the accompanying drawings,wherein:

Fig. 1 is a top view of the keyboard-type of photoelectric facsimiletransmitter provided with a permutation slide shutter;

Fig. 2 is a fragmentary perspective view of the permutation-slidearrangement;

Fig. 2 is a front elevational viewof the apparatus shown in Fig. 1 withparts broken away to plished by directing a beam of light through theshow more clearly the details thereof.

Fig. 4 is a sectional view taken on line i-l of Fig. 3; I

Fig. 5-is a sectional view taken on line 5--5 of Fig. 3;

Fig. 6 is a perspective view of the photoelectric cell and its housing;

' Fig. 7 is a sectional view of the photoelectric cell and housingtherefor;

Fig. 8 is a development of the scanning cylinder or light chopperwherein the apertures are etched in a metallic plate, and is a view ofthe inside of the unfolded cylinder, cut for unfoldment along the lineAA of Fig. 15;

Figs. 9, 10, 11, and 12 are fragmentary views of Fig. 13 is a schematicdiagram of the electrical the present embodiment, selector mechanism |5comprises six pairs ofcode bars l6 and I1, each their free ends formedwith oppositely offset lugs,

which are disposed on opposite sides of the pivot rod 2| and are spacedsome distance therefrom. One of the lugs of each rocker lever projectsforwardly into a notch on the edge of the associated circuit at thetransmitting station employing the through the circumferential row(developed along line |5-|5 of Fig. 8) corresponding to the characterillustrated in Fig. 14;

Fig. 16 is a plan view of a tape sensing mechanism adapted to controlthe facsimile transmitter similar to the one shown in Fig. 1;

Fig. 17 is an elevational view of the apparatus shown in Fig. 16;

Fig. 18 is a'representation of a portion of perforated tape;

Fig. 19 is a fragmental view of a modified form of keyboardphotoelectric facsimile transmitter substituting individual shutters forthe permutation bars;

Fig.20 is a partial elevational view of the. embodiment shown in Fig.19;

Fig. 21 is a sectional view taken on line 2 |2| of Fig. 20;

Fig. 22 is a cross-sectional view of a further embodiment of theinvention utilizing a concentrated beam of light;

Fig. 23 is a sectional view taken on line 23-23 of Fig. 22;

Fig. 24 is a sectional view taken on line 24-24 of Fig. 23;

Fig. 25 is a fragmental perspective view of an alternate form of mirroror reflector;

Fig. 26 is a schematic diagram of the electrical circuit at thetransmitting station when the scanning cylinder according to Fig. 11 is,employed, and

Fig. 27 is an enlarged sectionalview taken on line 2'|2'| of Fig. 3.

Having reference to Figs. 1 to 7 inclusive, which show one of theembodiments of the invention, the transmitting apparatus comprises abase portion N (Fig. 1) having at its forward part a bank of keys I2,arranged in the usual manner. Each of the keys i2 is carried on a keylever l3 all of which are pivotally mounted on a common pivot rod l4supported at the rear of the base portion ll. As is the usual practice,key levers |3 are biased upwardly by individual springs (not shown).Arranged below the key levers l3 and disposed transversely thereof is apermutation selector mechanism indicated generally as l5 (Figs. 3 and4). Selector mechanism i5 is of the form shown in U. S. Patent No.

code bar i6, and its companion lug projects rearwardly beneath thecompanion code bar With this arrangement, the depression of either codebar of the pair of bars 5 and I7 rocks the levers i8 and lifts thecompanion code bar. To the depending portions of the T-shaped rockerlevers I8 is articulated a longitudinally movable permutation bar 22.Thus, when the code bars i6 and i! are moved vertically in accordancewith the depression of a key lever l3, the permutation bar 22 individualto a pair of bars l6 and I1 is moved longitudinally.

Secured to each of the permutation bars 22 and vertically supportedtherefrom is a forked member 23. Articulated to each member 23 is adepending arm of a lever 24 pivoted on a common shaft 25. In thismanner, levers 24 are articulated to the permutation bars 22 and areadapted to be rocked about pivot shaft 25 to either of two positions.Each of the levers 24 has its vertical arm articulated to a slide member26. Slide members 26 are slidably supported at 21 and 28. The slides 26are each provided at the left end thereof with a vertical lug 29carrying at its free end a stud 3|. Each of the studs 3| (Fig. 2) isconnected to one of a series of thin flat permutation plates 32corresponding in number to the numbers of slides 26, namely six in thepresent disclosure. Each of the slides 26 is provided at the right endthereof (as viewed in Fig. 3) with a vertically directed lug 33.Cooperating with lugs 33 is a locking bail 34 pivotally carried onpivots 35 and 36 (Figs. 1 and 3) supported in bracket 31. Locking loop34 also is provided with an integral laterally extending arm 38 (Fig. 1)which carries at its outer end a cam follower roller 39 which cooperateswith a cam 4| carried on a shaft According to the operation of thedevice so far described, the depression of a key lever 3 sets the codebars l6 and H permutably in their upper or lower positions according tothe permutation code represented by the key lever depressed. Thissetting of the code bars l6 and I1 is transferred through the rockerlevers Hi to the permutation bars 22, thus setting the bars 22 in theirrightward or leftward position. This 'setting is transmitted by levers24 to slides 26 which in turn set the permutation slides 32 in theirrightward or leftward positions. When the slides 26 are so set, the cam4| operates in proper timed relation to permit bail 34, through follower39, to rotate counterclockwise to lock the slides 26 through theinstrumentality of their locking elements 33.

Located below the key levers l3 and operated thereby is a universalrelease bail 43 (Fig. 4) pivotally supported at each end by pivots 44.Fixed to bail 43 is an arm 45 which has pivoted at its extremity a tripmember 46. Trip arm 46 terminates in' a shoulder 47 which cooperateswith the pointed end formed on the depending arm 48 of a bell cranklever49 pivoted at to a bracket 52 mounted on the base portion Arm 53 of bellcrank 49 cooperates with arm 54 of a stop lever 55 pivotally carried onbracket 31. The vertical arm of lever 55 terminates in a shoulder 56which cooperates with a projection 51 on a stop disc 58 carried on shaft42. i

Upon depression of a key lever l3, universal bail 43 is actuated in a.counterclockwise direction to impart, through arm 45, leftward movementto arm 46 (Fig. 4). Arm 46, through its shoulder 41, actuates bell crank49 in a clockwise direction to impart counterclockwise rotation to 'stoplever 55. Arm 46 is provided with a cam portion 59 which coacts with aneccentric screw head 6l-so that in its leftward movement arm 46 isautomatically disengaged from lever arm 48. A spring 62 normally biasesthe arm 46 against the screw head 6|. counterclockwise rotation of lever55 permits the release of disc 58 and rotation of shaft 42.

Disc 58 is integral with a sleeve 63 loosely carried on shaft 42. I pairof projections 64 which cooperate with corresponding notches 65 in asleeve 66 secured to shaft 42. Compressed between flanges on sleeves 66and is a spring 61. In this manner sleeve 63 has slidable relation withshaft 42. Also fixed to shaft 42 is a flanged sleeve 68, and positionedbetween sleeve 63 and sleeve 68 and separated therefrom by frictiondiscs 69 is a gear 1|. Compression spring 61 acts through sleeve 63 tocompress or clutch the gear 1| between the friction discs 69, thusproviding a friction clutch between the gear 1| and the shaft 42. Gear1| meshes with a pinion 12 fixed to the shaft 13 of a motor 14. Theaforementioned cam 4| is integral with the sleeve 66.

' Shaft 42 is journaled at its right-hand end (as viewed in Fig. 1) inthe bracket 31, and at its left-hand end in the housing 8|. Fixed to theleft-hand end of shaft 42 is a member 82 arranged to carry or support ascanning cylinder or screen 83, in such a manner that the scanningcylinder or screen 83 is rotatable within the housing 8|.

Positioned within the scanning cylinder 83 is a photoelectric cell 84(Figs. 3 and 5), comprising a cathode 85 and a pair of anodes 86. Asshown in Figs. 6 and '7, the photoelectric cell 84 is contained within ametal cylindrical housing 81 from which'a'wide slit 88 has been cut tocorrespond to the size or opening of the light apertures, as willpresently appear. The right-hand end of cylinder 81 is left uncut andaffords a frictional support for the base 89 (Fig. 7) of thephotoelectric cell 84. The cylinder 81 is also slit at 9| and 92, sothat. the portions of cylinder 81 adjacent the wide slot 88 'may bepressed inwardly so that the photoelectric cell 84 is snugly held withinthe cylinder. The cylinder 81 is in turn frictionally held in a baseportion 93 which is formed at 94 to have a slidable fit in the housing8| as shown in Fig. 3.

As viewed in Fig. 5, housing 8| is cut off at 95 so as to leave anaperture or slot commensurate in length and width with the slot 88 ofthe cylinder 81. Adjacent to the face 95 of housing 8| is secured a bar96, which is provided with an elongated slotted hole 91 commensurate insize with the corresponding holes in cylinder 81 and housing 8|. Asshown in Figs. 1, 2, and 3, the slot 91 is further provided 'with aplurality of septums 98 which are spaced so as to provide a series oflight confining channels to correspond Sleeve 63 is provided with a andregister with the circumferential rows of apertures in the scanningcylinder 83. The function of septums 98 is to prevent light from leakingor escaping from one slot or light confining channel to an adjacentslot. This structure makes possible the use of. a long single-filamentlamp for a large number of scanning columns, as well as the use of along cathode photocell, and is also a factor in dispensing with theoptical system. Moreover, this structure increases the parallel natureof the rays striking the scanning cylinder and the photocell. Bar 96 isgrooved adjacent to housing 8|; to provide a guide and support for theplurality of permutation plates 32. Interposed between face 95 ofhousing 8| and bar 96 (as shown. in Fig. 2) is a thin plate 15.

A light source in the form of an incandescent lamp Hill is positionedadjacent the bar 96 on the side thereof opposite to the photoelectriccell 84. The photoelectric cell 84, the slots 88 and 91, the

slot in housing 8| and the lamp I are all arranged on a common centerline. The lamp N16 is carried on a suitable bracket 99 mounted on thebase portion Suitable electrical connections are, of course, providedfor the photoelectric cell 84 and the incandescent lamp I110. Thephotoelectric cell 84 has a long cathode and a long anode and the lampI60 has a long filament coextensive with the series of rows of apertureson the scanning cylinder 83.

For purposes of compactness the apertures in plate 15 are arranged intwo rows, the apertures 16 and 88 in the upper and lower rows,respectively, being staggered with respect to each other. An aperture 16is positioned to register with each light confining channel between apair of septums 98. Apertures l0| in the permutation plates 32 are alsoarranged in two rows, an apertural position being provided in each row,and

such positions being staggered as in the case of plate 15. However,since there is a position for each aperture, there is not necessarily anaperture in each suchposition, because of the fact that the presence orabsence of the apertures in the plurality of plates is determinedaccording to a permutation code. The reason for staggering the aperturesin order to achieve compact-ness is that in the permutation platearrangement there are two selective positions for each plate, so thatthe slots |0| must move longitudinally of its length a distance somewhatgreater than the length of an individual slot, and thus by staggeringthe apertures, a blank space is provided in plate 15 for the slots |0|when in its unused position.

According to the present invention, then, the plurality of permutationplates 32, instead of being provided with the usual notches in theiredges. are provided with apertures llll therethrough which are so spacedthat upon movement of the plates permutably, a different series of holesor apertures therein registers for each permutation and admits lightthere'through which-activates the photoelectric cell 84. This activationof the photoelectric cell 84 is further controlled by the rotatingscanning cylinder 83, the apertures in each row, as will presentlyappear, representing a particular character.

Having reference to Fig. 8, the scanning cylinder 83 is shown developed.Fig. 8 is a development of the scanning cylinder 83 out along line AA inFig. 15 and unfolded so as to view the developed cyli der in thedirection of the arrow H0 in Fig. l and thus to present the insidesurface oi the cylinder to view in Fig. 8. Since the cylinder 83 rotatesin a counterclockwise direction, as viewed in Fig. 15, it is obviousthat the movement of the apertures I02 of Fig. 8 past the openings inthe permutation plates 32 is downwardly, and hence this relative motionis indicated by I20 in Fig. 8. Each of the vertical rows of apertures inthe development is analogous to a disc I35 shown in the aforementionedPatent No. 2,000,083, the high radii of the scanning disc I35 of saidpatent being represented in scanning cylinder 83 to the apertures I02.According to one mode of manufacture, the plate used to produce thescanning cylinder 83 is sensitized photographically and the signalsymbols represented by the apertures are photographed thereon from amaster chart, and through an etching process the apertures I02 arechemically formed or produced by etching completely through the plate.Referring to Figs. 8 and 14, the vertical rows I03 of apertures I02(Fig. 8) are designed according to a method of prescanning; that is, thecharacter to be transmitted is divided into any desirable number ofsending units of area. The several units of each character thus createdare assigned to the apertures I02 individual to that characterrepresented by a row I03 in the order of scanning and the dark units ofthe character shown in Fig. 14 are created under the control of theapertures which admit a beam of light to the photocell to send a signal.In this connection, it is observed in Figl 8 that, because of thestaggered relation of the slots or openings I6 and 80 in plate 15 (Fig.2), the rows I03 in the scanning cylinder 83 are also alternatelydisplaced circumferentially,for the purpose of timing all of theimpulses properly. This feature also makes possible the use of the samestop slot I'I (Fig. 2) for both sets of signals. For example, the rowsof striations of apertures indicated I8 in Fig, 8 cooperate with theupper row of slots 80 shown in Fig. 2, and the rows or striations ofapertures indicated I in Fig. 8 cooperate with the lower row of slotsincluding slots 76 and ii in Fig. 2. The aperture I23 (Fig. 8) forcontrolling the stop signal, and the stop slots ii in the permutationplates 32 cooperate with the lower slots 16 (Fig. 2). It should be notedthat with the form of scanning cylinder shown in Fig. 8, the stopimpulse occurs only in one position or row. Thus, if a stop impulse issupplied for each character as in the form of scanning cylinder shown inFig, 9, the cylinder would be cut substantially in two and would not besufliciently rigid. Hence, if a metal scanning cylinder is employed, itis considerably stronger when the stop and start impulses aretransmitted in one position as shown in Fig. 8.

For an example of prescanning, the letter "R is shown in Fig. 14together with the blank area between the letter shown and the precedingletter. It is preferred to leave a blank'interval also below the letterso that when the letters are printed in rows one above the other, therewill be a space or a white line between the rows. According to thepresent disclosure, this total areafis divided into 450 units of area,25 units high and 18 units'wide. It is, of course, understood thatsaidarea may be divided into any convenient number of unit areas, dependingupon shown in Fig. 15 which is a section of scanning aaeauea cylinder 83taken substantially on line I-I5 of Fig. 8, the'cross section beingtaken of the cylinder and not of the flat development.

Scanning begins at the unit I05 (Fig. 14) and progresses vertically tothe unit I06, continuing immediately at unit I01, again at unit I08, andagain from unit I09 to III, completing the scanning of seventy-eightsuccessive white units, re-

, sulting in the unapertured portion II2 (Fig.

of the scanning cylinder 83. The scanning of 'the black unit extendsfrom unit I I3 to unit I I4 (Fig.

. 14) resulting in the aperture II5 (Fig. 15). Then the three whiteunits I I6 to I I1 result in the unapertured portion I I8, and thetwenty-two black units II9 to I2I result in the apertured portion I22(Figs. 8 and 13). Continuing in like manner, scanning of the total areaof Fig. 14 results in the total apertured and unapertured portions orarcs on the edge of the scanning cylinder 83 (Fig. 15). As previouslyindicated, the section of the scanning cylinder 83 shown in Fig. ,15represents the letter "R.. Similarly, other cross sections taken throughother vertical rows I03 shown in Fig. 8 would represent othercharacters. Every character code row has the initial starting portionH2. The vertical row in Fig. 8 including the long aperture I23 is therow for the stop signal.

Instead of producing the scanning cylinder 83 from a metal plate, asuitable flexible transparent material, such as a photographic film, maybe employed. According to this method a large scale drawing in black'andwhite may be prepared representing the cylinder in development. Then aphotographic copy, positive or negative, as required according to themethod of transmission used is reproduced to the exact size desired.Figs. 9 and 10 represent a negative photograph wherein the transparentportions are analogous to the solid portions in Fig. 8. Thisphotographic film is then formed into a cylinder and mounted insubstantially the same manner as cylinder 83 shown in Fig. 1. Aspreviously indicated, in the form of scanning cylinder shown in Fig. 9,the stop impulse I24 is embodied in each circumferential row. Thearrangement shown in Fig. 9

is especially adapted to transmission with a continually rotatingscanning cylinder, wherein it is desirable that the stop condition(exemplified by opaque portion I24, Fig. 10) is a no-light condition,since otherwise special means would be required to illuminate thephotoelectric cell continuously when no signals are to be transmitted.Thus according to the method exemplified in Figs. 9 and 10, the scanningcylinder is produced by making the image on a translucent material sothat the material will be sufiiciently strong. The electrical circuitemployed with the scanning cylinder shown in Figs. 9 and 10 is the sameas that illustrated in Fig. 16 of copending application, Se-

rial No. 48,098, filed November 4, 1935 by L. M. Potts, in which event,the marking and spacing light conditions on the photocell are reversed.The noted circuit is similar to the circuit illustrated in Fig. 13herein, except that the normal grid bias of the electronic tube in thefirst stage of amplification is changed from a slightly negativecondition to a more negative condition, and the photocell has beenconnected in such a: manner as to bias the grid positively when lightfalls upon the photocell. In both of said circuits the same effect isobtained upon the tube of the sec- 0nd stage of amplification, so thatfor marking signals the same kind or nature of signal is transmittedover the line wire. The form of scanning cylinder shown in fragmentaryviews, Figs. 11 and 12, is also a photographic film. According to thismethod, instead of making the transparent portions clear, they are madewith a series of lines so as to give an alternating current effect. Acircuit for this method of scanning is shown in Fig. 26, and will belater described.

Upon each permuted setting of the permutation plates 32, an alignment ofholes in said plates will result opposite the circumferential, row ofapertures I02 selected, through which the beam of light from the lamp 98is permitted to pass to impinge upon the photoelectric cell 84. As thescanning cylinder 83 makes one complete rotation, a series of markingand spacing impulses corresponding to the particular arrangement ofapertures I02 in the selected circumferential row is transmitted, underthe control of the photoelectric cell, over the signal line to operate afacsimile printer.

The type of facsimile printer adapted to be operated from the signalstransmitted by the transmitter just described is as shown in U. 8.Patent No. 2,000,083. In Fig. 13 is illustrated a circuit arrangementemployed in conjunction with the transmitting apparatus just described.With this circuit arrangement a system is provided in which the platecurrent is reduced to zero in at least two places in a multi-stageamplifier, so that the on and off conditions are not affected by valuesof thecontrol light above or below a certain value; that is, theamplifier used with the photoelectric transmitter disclosed has twostages. In the first stage, a certain amount of light cuts off the platecurrent, and any additional illumination has no effect in altering thefinal output 'of the amplifier, the current in the second stage beingdetermined by the local adjustment of the circuit. When the light fallsbelow a certain value, sufficient current fiows in the plate circuit ofthe first electronic tube to reduce the current in the plate circuit ofthe second electronic tube to zero, and any further degrees ofillumination have no effect on the final output.

In the circuit shown in Fig. 13, the photoelectric cell is shown at 84,and as is known, the impingement of light upon the light sensitivecathode 85 causes the emission of electrons therefrom which fiow towardthe anode or positive electrode 86 of the photocell. The cathode 85 issupplied with operating voltages from source I34 and changes in theelectron stream flowing within the cell due to the varying lightintensities falling thereon, will cause varying potential differences tobe setup across a resistance I35 which is connected in series with thephotocell electrodes. The resistance I35 is also connected to the gridcircuit of a multi-electrode electronic tube I36, having a cathode I31and a control grid I38. The resistance I35 and the cathode I31 may be soconnected to the source I34 as to provide a normal grid biasing sourceI39. The cathode I31 is of the hot cathode type and is heated by afilament I4I connected to a source of current I42, for example, thesecondary circuit of a transformer I40. As 'thus far described, thecircuit comprising source of current I34, photocell 84, and resistanceI35, is the' source or input circuit for the grid control circuitcomprising grid I30, cathode I31, conductor I43, biasing source I39, andresistance I35. The plate circuit of electronic tube I38 includes theportion of potentiometer for I34 included between taps I44 and I45,conductor I43, cathode I31, plate I46, resistance I41, andconductor/I48,

and is the source or input'circuit for the grid control circuit of asecond electronic tube I49 comprising a grid I5I, cathode I52, and aplate I53. The control circuit for grid I'5I includes portion of sourceI34 included between taps I45 and I54, conductor I 48, resistance I41,grid I5I, cathode I52, and conductor I55. The plate circuit of tube I49extends from portion of source I34 between taps I54 and I58, conductorI55, cathode I52, plate I53, thence through winding of line relay I51,through variable resistance I60 and back to source I34. Variableresistance I80 is provided to control the plate circuit of the .tubeI49. Cathode I52 is heated by a filament I61 which, like filament I4I,may be connected to the secondary of transformer I40. The current forthe exciter lamp I00 may also be derived from a secondary of transformerI40.

Apertures I02 in the scanning cylinder 83 are indicative of markingsignals, and the presentment of an aperture into the scanning regionwill permit the impingement of the light beam upon the cathode of thephotocell 84. The condition of the transmitting apparatus, for example,that-shown in Figs. 1, 3, and 4, during cessation of transmission ofsignals is such that the aperture I23 permits light to pass onto theoathode 8-5 of photocell 84. This is possible because the apertures inplates 32 associated with the stop aperture I23 are of such length thatno matter what their selective position may be there is always anopening 11 (Fig. 2) to permit light to pass through the aperture I23 forthe stop impulse. Therefore, the scanning cylinder 83, through its rowincluding aperture I23, exercises sole control over the passage of lightthrough the permutation plates 32 at the stop impulse position.Therefore, during the 'stop period, the light from the lamp I00 passesthrough the aligned holes 11 in the permutation plates 32, thencethrough the aperture I23 of the scanning cylinder 83 onto the cathode 85of photocell 84, thereby stimulating the emission of electrons therefromand thus permitting current to flow in the source circuit which iscoupled by means of resistance I35 to the control circuit for grid I38.-The grid I38 is influenced thereby so as to cut off the flow ofelectrons'from cathode I31 to plate I48 and thus reduce the platecircuit of the tube I38 substantially to zero. Cutting off the platecircuit of tube I36, which is the source circuit of the grid controlcircuit of tube I49, renders the grid I 5| more positive and increasesthe flow of current in the plate circuit of tube- I49 sufficiently. toactuate relay I51 to hold the armature I58 thereof against contact I59connected to battery IBI to impress marking current on the line wireI62.

When the transmission of signaling impulses over the line I62 (Fig. 13)is to be initiated, the scanning cylinder 83 is permitted to rotate inresponse to the depression of a key lever I3 to transmit first a startimpulse of spacing nature of duration commensurate with thegwidth ofportion IIZ (Fig. 14) on the scanning cylinder shown developed in Fig.8. It will be observed that, although an alignment of holes 11indicative of the stop signal always obtains in the permutation plates32 irrespective of their selective or permutative positions, the beam oflight is cut off by the scanning cylinder 83 as it begins the aforesaidrotation. After the portion 2 has been traversed, the code impulses ofmarking and spacing nature, depending upon the presence /or absence ofapertures I02 in the circumferential row corresponding to the selectedcharacter, are transmitted. The particular character to be transmittedis governed, of course, by the setting of permutation plates 32corresponding to the key lever depressed to efi'ect an alignment ofholes in said plates in registry with the circumferential row in thescanning cylinder corresponding to said transmitted character. Becausethe circumferential row I80 on cylinder 83 embraces stop slot I23, andan opening 11 in registry with said row always obtains, the light beamdirected upon the photocell 84 during the stop period is cut ofiinvariably for a predetermined time interval indicative of the startimpulse interval commensurate with the portion IIE on the scanningcylinder 83. In this connection it is noted that the staggering of holesin plate I5 and permutation plates 32 is consistent with the staggeringof the. circumferential rows in the scanning cylinder 83. For example,if the cylinder 83 were to be rotated so that the actual beginning of asignal row 18 (Fig. 8) were in registry with its corresponding slot inthe lower row of holes 16 and let in plates and 32, respectively, thebeginning of a row 19 will be in registry with its corresponding slot inthe upper row of holes 16 and mi in said plates I5 and WI, respectively.

The cutting off of the light of photocell 8G influences the grid I558 soas to permit the flow of current in the plate circuit of tube Ito,thereby influencing the grid Isl of tube MI to render grid IE I morenegative, thereby cutting off the flow of current in the plate circuitof tube use, and hence actuating relay I51 in such a manner as to permitspring Itl to move armature I53 to the dead contact I63, whereupon aspacing impulse will betransmitted over the line wire I62. The signalsthus transmitted over line wire I52 may be utilized to control theoperation of a facsimile printer or recorder, for example, of the typedisclosed in U. S. Patent No. 2,000,083. The signals transmitted, forexample, are directed through a line coil I65 of the facsimile printerthence to ground. The facsimile printer disclosed schematically in Fig.13 comprises the printing or recording wheel I66 which is concurrentpotential of opposite polarity is applied to the points 361 and 369 ofresistance 310. When no light is applied to the photoelectric cell 36Ithere will be on the line 31I312 a direct current from battery 313. Whenthe photoelectric cell is illuminated by chopped light (under thecontrol of the striated portions of the cylinder shown in Fig. 11)' andalternating current is generated, the alternating current will berectified by rectifier 365, and the output is such as to produce apotential about twice the potential of battery 313 so that there will besupplied on line 31I- 312 polar signals for the operation of a receiver31%. When a scanning cylinder according to the form shown in Figs. 11and 12 is used, the width of the slots or apertures in plate 15 (Fig. 2)should be commensurate with the striations I25 in Fig. 11, so as toobtain sharp outlines of the alternations or light changes.

Modifications In Figs. 16 and 17 is shown a tape controlledphotoelectric facsimile transmitter. With this embodiment the scanningcylinder arrangement a .with a worm gear I19 fixed to the main operatingshaft I15. Fixed to the main shaft I15 is the driving portion I'Iil of asingle-tooth grab clutch,

the driven portion ml of which is slidably mounted on shaft I15. Thedriven portion IBI has engagement in tongue and groove manner with a camsleeve I82. Secured to shaft I15 for constant rotation therewith is apinion I83 which trolled through a start-stop clutch. As disclosed insaid patent, the printing or platen wheel I66 is provided on itscylindrical surface with symmetrical spiral lmife edges which cooperatewith an operating member or platen its, having a knife edge arrangedtransversely of the tape III. Platen its moves with the line coil memberI65 and reciprocates vertically therewith in response to the receivedsignals. In responseto a marking signal, the line coil will be actuatedupwardly, bringing the platen Its against the printing wheel; then, uponreceipt of a spacing signal the line coil moves downwardly under theaction of gravity or by means of a return spring, bringing the platenagainst a stop.

The circuit shown in Fig. 26 is used with a photoelectric transmitter inwhich a scanning cylinder or light chopper embodying the characteristicsillustrated in Figs. 11' and 12 is employed. llvhen the photocell 3% isilluminated by choppedlight, alternating current is delivered from thesecondary of transformer 362 to the grid of an amplifying tube 363, theplate of which meshes with a corresponding pinion or gear Ills fixed toa cross shaft I85. Shaft I85 is comparable to or analogous with shaft 12of the form of the invention shown in Figs. 1 to 7. Shaft its rotatesconstantly and carries a scanning cylinder (not shown). The scanningarrangement applicable to the presently described form of the inventionis substantially similar to the scanning arrangement previouslydescribed, except that the scanning cylinder or light chopper is of theform, for example, as shown in'Figs. 9 and 10, wherein a start signaland a stop signal are embodied in each character signal, and whereinprovisions have been made for effecting the transmission of such signalsfrom a continuously rotating scanning cylinder mounted on shaft I85.Clutch portion I8I is provided with a flange ltd, which in turn isprovided with a cam portion I81 cooperating with arm I88 of a clutchrelease lever I39 pivotally carried on pivots |9I and I92. The camsleeve I82 carries integrally thereon'a tape feed control cam I93, atape sensing control cam I96, a special shutter cam I95, and a transfermechanism operating cam I98.

The tape sensing mechanism or record reader comprises a series'of tapefeeler levers I91, so

. called because of their function in sensing the attributes of atransverse line of tape perforations. Feeler levers I91 are providedwith arms points 366 and 361 on a resistance 368. A direct I98 whichcarry feeler pins I99. Pins I99 are adapted to be projected upwardlythrough a slot 20I in a tape guide 202, slot 20I being substan-- tiallycoextensive with the width of the tape. The tape feeler levers I91 arealso provided with projections 203 which are engaged by a bail 204 forperiodically withdrawing the levers I91 in accordance with eachsuccessive feeding or stepping of the record tape. The bail 204 moves aspart of a bell crank structure 205 which is actuated, through itsfollower roller 206 by the tape sensing or record reading control camI94. The series of feeler levers I91 are rockable upon a common shaft200. Each of the feeler levers I91 is provided with a pair of abutments201 and 208 which cooperate with abutment lugs 209 and 2I I terminatingarms 212 and 2I3 of a transfer lever 2I4. The transfer T-levers 2I4 aresupported on a common shaft 2I5 which in turn is carried by one arm of abell crank lever 2 I6 pivoted at 2I1, the end of the other arm of whichcarries a roller 2I8 spring-urged to follow the peripheral surface ofthe transfer control cam I96. The cam I96 has an apex substantially asshown in Fig. 17, and when it is rotated together with shaft I15 itimparts a regular and reciproeating motion to the 1ever2IB and itsassociated T-levers 2I4. The depending arms of T-levers 2| 4 terminatein disc-shaped portions 2I9,

through which said T-levers are articulated to connecting bars 22Iindividual to each T-lever 2I4. Connecting bars 22I are supported insuit-.

able guideways (not shown) for longitudinal and parallel movement.

In accordance with the timed action of bell crank lever 205 and transferoperating lever 2I6, the set of feeler lever I91 will first be permittedto rotate counterclockwise, during which time those levers I91 whosepins I99 are not blocked by the record tape 222 (Fig. 18), but which arebrought into registration with a perforation thereof, will be permittedto rotate until their respective shoulders or abutments 208 registeropposite the abutment lugs 2II of the transfer levers 2I4, while theothers which are not permitted so to do will remain in the positionshown in Fig. 17, with their shoulders 201 in registration with theabutment lugs 209. Immediately following the establishment of thiscondition, the cam I96 which moves lever 2I6 counterclockwise forces theseveral transfer T-levers 2I4 into engagement with their respectivefeeler levers I91 and, depending upon which of the two positions thefeeler levers I91 happen to assume, T-levers 2I4 will be correspondinglypositioned and will impart a similar positionment to their associatedbars 22I. perforations present in each transverse align- In this mannerthe combination of 7 ment in the tape is translated simultaneously to toregister with the central perforations 229 of the control tape 222 inaccordance with the Wellknown practice. In this manner the single shaftI15 through its cam sleeve I82 operates all of the mechanical agenciesthat control th record.

' reader or tape sensing mechanism.

Particular attention is directed to the fact that all of the feelerlevers I91 are brought back to a normal or starting position atsomedefinite point in each cycle of operation, yet the transfer levers 2I4and articulated slide bars 22I are not restored at this time, but may beset in conformity with a new code combination regardless of theirprevious position. This practice permits of an overlap in the operationof the two sets of levers,

namely, feeler levers I91 and T-levers 2I4, and allows the permutationplates 232 (comparable to the permutation plates 32 shown in thefirst-described embodiment of the invention) maximum time of rest duringeach cycle of operation.

Connecting bars 22I are each provided at their left end (as viewed inFig. 17) with an upstanding lug terminating in a disc-shapedlportion233, having pivotal articulation with a corresponding series of slidebars .234, namely, six in the present embodiment, corresponding to thesix code signal perforations 235 in the tape 222. Each of the slide bars234 is provided with a vertically extending lug 238 which carries fixedthereto a stud 231. of each stud 231 is a permutation plate 232. To

permit slidable movement of plates 232 by their I respective studs 237,the plates 232 are slotted in well-known manner. The permutation plates232 are provided with apertures similar to apertures IOI inplates 32.The apertures, therefore, in plates 232 are arranged in permuted mannerso that from each permuted setting of plates 232 an alignment ofapertures will occur to permit the light from the exciter lamp toimpinge upon the photoelectric cell and to be scanned by the propercircumferential row of apertures in the scanning cylinder.

In addition to the six code shutters or permutation plates 232, there isan additional plate or shutter associated with an extra slidebar 238(Fig. 16). The function of the shutter associated with the slide 238,when in its extreme right-hand position, is to close all of the lightapertures and so prevent the transmission of signals, even though shaftI85 (with the scanning cylinder carried thereon) is rotating. Since thestop signal is a no light condition, the scanning cylinder must be theopposite of that for the keyboard facsimile transmitter described inconnection with Figs. 1 to 8. scanning cylinder must be of the typeshown in Figs. 9 and 10, wherein translucent portions are provided forthe start and other spacing signals. Slide bar 238 is pivotallyarticulated at its right-' hand end (Fig. 17) with the depending arm ofa lever 239 pivoted at 240. Also mounted on pivot 240 is a lever 24I,carrying a follower roller 242 normally held against the periphery ofcam I95 through the action of spring 243. Levers 239 and MI are normallybiased toward each other by a spring 244. Carried on shaft I is a cam245 which cooperates with a follower roller 246 carried on a lockingbail 241. Each of the slide bars 234 and 238 are provided with avertical locking lug 248 which cooperates with the locking bail 241, sothat as the bars 234 and 238 are operated to their rightward or leftwardpositions by the connecting bars 22I, the permutative setting ismaintained until, at a proper time, a new setting is permitted to be setup in the selector bars. In this connection; it is observed that thearticulated lever 239 and 24I, along with the spring 244, serves itspurpose by being put undentension when shaft I15 comes to rest. but the:ide bar 238 is held by locking lever 241 Fixed to the opposite ends Inother words, the

in its light conducting position, so that the signal being transmittedwill be completed; but will close as soon as the stop impulse isreached, whereupon cam 245 acts to release locking lever 2M. Thereafter,the scanning cylinder will rotate without transmitting any signals ofany kind until the sleeve I85 is again started.

ing. Cam I96 in its rest position acts to hold the bell crank lever 285in. its counterclockwise position, thus holding the feeler levers I91 intheir clockwise position with the feeler pins I99 withdrawn from thetape 222. Cam I93 in its rest position acts to hold lever 225 in itsclockwise position, and cam I96 acts to hold the transfer operatinglever 2I6 in its clockwise position.

A paper tension control arm or taut tape lever 225i is pivotallysupported at252 on a bracket 253 and. is shown in Fig. 17 in itscounterclockwise position. In this position, which is the taut tapeposition, an interfering member 256, pivotally supported at the left endof taut tape lever I, is held out of cooperative relation with dependingarm 255 of a bell crank lever 256. Bell crank 256 is pivotally mountedon pivot 251i and is normally biased by a spring 258 in a clockwisedirection to hold a follower roller 259 carried at the end of thehorizontal arm of the bell crank lever 256, against the periphery of acam 26I fixed to the shaft I85. Since the shaft I85 is constantlyrotating, the constantly rotating cam 26I will continually rock the bellcrank lever 256, thus oscillating the arm 255; but when the tape is tautand the lever 25I is held in its counterclockwise position as shown inFig. 17, the toe or tip 262 of the lower extremity of member 255, beingout of register with the lever 255, will not be actuated thereby, andthe lever I68 will.be held in its clockwise position so as to hold thedriven portion I8I of the clutch out of engagement with the drivingportion I16. However, when the tape becomes slack and the taut tapelever 25I assumes its clockwise position, the member 256 will be raisedto bring the toe 262 upwardly into register or cooperative relation withthe oscillating arm 255 of bell crank lever 256', so that upon itsoscillatory movement lever arm 255 will, through the toe 262, impartcorresponding movement to the depending arm 254i. Incidentally, thisactuation of lever arm 254i is not imparted to the taut tape lever 25Ibecause of the fact that the depending arm 254i is loosely mounted onlever 25L Arm 256i is arranged to be slidable between a pair of lugs 268integral with the clutch lever I69, and is thus articulated to leverI89. Accordingly, upon each oscillation of arm 255, the clutch releaselever I89 will likewise be oscillated, due to the cooperaitverelationship between arm 255 and lever 256 through the agency of the toe262. Thus, since shafts I65 and I75 are rotating at the same rate ofspeed, the rotation of shaft I15, and hence cam sleeve I82, will besubstantially continuous during $18- nal transmission. It is thereforeseen that .the

base portion 265 area plurality of key levers 214 operating cams I99,I94, I95, and I96 will not be released for operation if the tape istaut, since,

then the interfering member 254 will be in a position whereby itsprojection or toe 264 is out of register with lever arm 255. Owing totheir particular construction, levers 256 and 254 perform the functionof preventing any split signals, by insuring a single rotation of clutchI8I per signal. It is observed that by providing a singletooth grabclutch, sleeve I82, during signal transmission, will rotate in properphase relation with shaft I85.

, Assuming that signals are being sent by the record reader, the camsleeve I82 makes one revolution for each code signal. Upon theinitiation of rotation of sleeve I82, the cam I95 thereon begins torotate to bring its apex out of register with the follower roller 242whereupon spring 293 rotates the compound levers 2M and 239 clockwise tobring the slide 238 to its leftward position, in which position theshutter slide 232 associated therewith is also actuated to its leftwardor light conducting position, whereat its apertures permit light to betransmitted, through any of the aligned apertures in the remainingpermutation plates 232, from the light source onto the phototelectriccell. At the end of each revolution of the cam I95, the slide 238, whenpermitted by the lever 291 as previously described, is returned to itsrightward position to bring the shutter slide 232 associated therewithto its rightward position to shut off all the light apertures. Again,when the tape is taut and the member 256 is held in its lowermostposition whereby shaft I85 rotates continuously and the cam sleeve I82is arrested in its rotation, the slide 238 is held in its rightwardposition and the permutation plate 232 associated therewith acts to shut011 all the apertures in the remaining plates regardless of thepermutative setting imparted thereto by the connecting bars 22!.

As previously indicated, the stop condition is a no light condition andthe signal controlling characteristics of the scanning drum are reverseto those for the transmitter shown in Figs. 1 to 8; that is, accordingto the modified form, spacing signals are represented by the aperturesinstead of the solid portions in the scanning cylinder. Accordingly, themarking and spacing conditions are reversed on the photocell, and thecircuit therefor is similar to the circuit illustrated in Fig. 13,except that, as previously alluded to, the normal grid bias of theelectronic tube in the first stage of amplification is changed from aslightly negative condition to a more negative condition and thephotoelectric cell is connected in such a manner as to bias the gridpositively when light falls upon the photocell.

In Figs. 19 to 21 is shown another modification of the presentinvention. In this form of the photoelectric cell. A motor 266 ismounted on the base portion 265 and has a shaft 261 carrying a pinion268 having meshing engagement with a worm gear 269 loosely mounted on across shaft 2'. Integral with gear 269 is the driving ortion 2712 of agrab clutch 213. Carried in the pivotally mounted on a common shaft 215supported in the rear portion of the base 265. A universal bail member216 pivoted at 211 is located beneath the key lever 214 and is adaptedto span said key levers for cooperation therewith. Fixed to theuniversal bail 216 is a bracket 280, to the extremity of which ispivoted a clutch release am 281, comparable to clutch release arm 46shown in Fig. 4. Similarly, clutch release arm 281 is provided at itsend with a shoulder 282 cooperating with the pointed end of a dependingarm 283 of an intermediate lever 284 pivotally supported at 285 to abracket 286 mounted on base portion 265 (Fig. 20). Lever 284 is alsoprovided with an arm 281 carrying on its end a follower roller 288 whichcooperates with arm 289 of a clutch release lever 291 pivoted at 292 toa bracket 293 mounted on the base 265. Clutch release lever 291 isprovided with a fol lower arm portion 294 which cooperates with a cam295 conformed on a flange 296 of the driven portion 291 of grab clutch213. A spring-298 compressed between the flange 296 and a collar 299tends to force the driven portion 291 of clutch 213 rightwardly (asviewed in Fig. 20) into meshing engagement with the driving portion 212whenever the clutch release lever 294 is disengaged from the cam portion295. Thus it is seen that when a key lever 214 is depressed, the bail216 is rotated counterclockwise to impart leftward movement to the arm281 which 2 causes the shoulder 282 to actuate, through its cooperationwith arm 283, the lever 284 clockwise which in turn impartscounterclockwise rotation to the lever 289 to effect the release of thedriven portion 291 of clutch 213 so that the spring 298 will carry theportion 291 intoengagement with the driving portion 212, therebyimparting rotation to shaft 215.

To the left end of shaft 211 as viewed in Fig. 19 is fixed the scanningcylinder 300. Scanning cylinde: 301 is arranged to rotate within ahousing 302 which is provided with a long slot or opening 303.Positioned within the scanning cylinder 301 is a photoelectric cell 309comparable to photoelectric cell 84 shown in Figs. 5 and 7. Aspreviously mentioned, there is associated with each key lever 216, ashutter 305. The shutters 305 are arranged in juxtaposition in front ofthe opening 303 so that when all of the shutters 305 are in their upperposition all of the light will be shut out from the photoelectric cell304. As shown in Fig. 21 each of the shutters 305 is integral with aslide portion 306 which is guided in a comb or guide portion 30?. Thelower portion of slide 306 is articulated to its associated key lever214 through a pin and slot connection. A spring 308 is distended betweeneach slide member 306 and a spring bar secured to the comb or guidemember 301. In this manner, the key levers are held or maintained intheir horizontal position. Each of the slides 306 is provided with a lug309 which cooperates with a locking bail 311. Upon the depression of akey lever 214 and the release of the clutch 213 for rotation, the bail311 is rotated counterclockwise to hold the operated slides 306 in theiroperated position under the control of a cam 312. The timing of cam 312is such as to lock the depressed key lever-in its operated position andto lock the unoperated key levers in their unoperated position duringthe period of transmission of the facsimile signal. Suitably mounted onthe base portion 265*is the electric'lamp 313. The axes of course,coincident with the opening 303 in the housing 302. Each of the shutters305 is provided with a slit or narrow aperture 314, which is normallydisposed, when the key levers 214 are in their horizontal or unoperatedposition,

above the opening 303, so that upon the depression of a key lever 214the opening 314 of its associated slide 305 is brought downwardly intoregister with the opening 303 into the path of the light beam from lamp313.

Another form of the invention is shown in Figs. 22 to 25, and is a.variant of the form shown in Figs. 19 to 21. Accordingly, those partswhich are common to both forms are not shown nor described and referenceshould be had to the form shown in Figs. 19 to 21 for a completeunderstanding of the form shown in Figs. 22 to 25. On the shaft 321(which is comparable to shaft 211 inFig. 20) is fixed the scanningcylinder 322. Scanning cylinder 322 rotates within a housing 323 whichis suitably mounted on the base portion 324. Fitted into the open end ofhousing 323 is a flanged disc,325, whichcarries rigidly therein the endsof a plurality of transparent light carrying rods 326, such as quartz orother material oflike optical properties. The housing 323 is providedwith a series of openings 321 ar-' hold the key levers 329 in theirhorizontal or unof the photoelectric cell and the lamp 313 are, 7

operated position. The slides 331 are slidably supported in a guidemember or comb 335 mounted on the base portion 324. Slides 331 are eachprovided with a shutter portion 336 contiguous with the housing 323 andguided by a plate 331. The shutters 336 act to cut off the beam of lightto the photoelectric cell when the key levers 329 are in theirunoperated position. Also, slides 331 ar each provided with an arm 338terminating in a reflecting surface 333. As indicated in Fig. 23, thereflecting surface 339 is disposed at substantially an angle of 45degrees with the plane of the-slide 331, as well as with the beam oflight produced by the optical system 351.

The optical system 341 comprises a housing 342 in which is supported anelectric lamp 343 and a condensing lens 344, as well as a lens 345, forproducing a concentrated beam of light with as nearly parallel rays aspractical. The reflecting surface 339 is normally maintained above thebeam of light, indicated at 346 in Fig. 22, when the key levers are intheir horizontal -or unoperated position.

rod 326 and thence onto the cathode of the photo-- electric cell 328;and as the scanning cylinder 322 rotates a single revolution, the lightbeam is cut non-operated positions simultaneously so as to hold a singlekey and slide operated during the transmission of a character signal.

In Fig. 25 is shown an alternate form of refiecting surface comprisinga. reflector 355 mounted on an arm 356 comparable to arm 338 of slide33!. With this construction the reflector 355 may be made of highlyreflective material; that is,-the beveled surface 351, which wascomparable to surface 339, may be made from a material different fromthe material composing the supporting structure, and such as will take ahigh polish.

What is claimed is:

1. In a facsimile transmitter, a photoelectric cell, a scanning devicehaving a plurality of areas, each area corresponding to a character andhaving portions with different light controlling abilities arrangedaccording to the character represented, means to select an areaaccording to the character to be transmitted, means to activate thephotoelectric cell according to the light controlling abilities of thedifferent areas, and means to generate signals according to theactivation of the photoelectric cell.

. 2. In a keyboard facsimile transmitter, a series of keys, a,photoelectric cell, means to activate said photoelectric cell, a screencontaining a representation of the signal impulses to be transmittedformed as a series of groups of transparent or opaque portions, eachgroup specific to a character, means controlled by said keys wherebysaid screen is passed between said activating means and saidphotoelectric cell so as to cause said representation of the impulses toaffect said photoelectric cell.

3. In a keyboard facsimile transmitter, a series of keys, aphotoelectric cell, means to activate said photoelectric cell, a screencontaining a representation of the signal impulses to be trans-.

mitted formed as a series of groups of transparent or opaque portions,each group specificto a character, means controlled by said keys wherebysaid screen is passed between said activating means and saidphotoelectric cell so as to cause said representation of the impulses tocontrol the generation of signals according to the activation of thephotoelectric cell.

4. In a keyboard facsimile transmitter, a series of keys, 2.photoelectric cell, means to activate said photoelectric cell, ascanning cylinder containing a representation of the signal impulses tobe transmitted formed as a series of groups of transparent or opaqueportions, means controlled by said keysfor releasing said scanningcylinder for one revolution only. and a shutter means controlled by saidkeys efiective when operated to cause said activating means to influencesaid photoelectric cell in accordance with one of said groups oftransparent'and opaque portions.

5. In a photoelectric transmitter, a character member having opaque andtransparent portions arranged in lines, a single line for eachcharaaeaeea the lines on the character member, and means to activate thephotoelectric cell for the duration of a signal interval according tothe character line selected.

I 6. In a facsimile transmitter, a photoelectric cell, a scanning devicehaving opaque and transparent portions arranged in a series of lines,one for each character to be transmitted, an exciter lamp adapted toactivate the photoelectric cell, means to select a character line, meansincluding the'scanning device to successively modulate the effect of theexciter lamp on the photoelectric cell according to the character of theline selected.

7. In a facsimile transmitter, a photoelectric cell, a scanning devicehaving a plurality of areas, each area corresponding to a character andhaving portions with different light controlling abilities arrangedaccording to the character represented, shutter means to select an areaaccording to the character to be transmitted, means to activate thephotoelectric cell according to the light controlling abilities of thedifferent areas, and means to generate signals according to theactivation of the photoelectric cell.

8. In a facsimile transmitter, a photoelectric cell, a scanning devicehaving a plurality of areas, each area corresponding to a character andhaving portions with different light controlling abilities arrangedaccording to the character represented, permutation means to select anarea according to the character to be transmitted, means to activate thephotoelectric cell according to the light controlling abilities ofthe'difierent areas, and means to generate signals according to theactivation of the photoelectric cell.

9. In a facsimile printing telegraph transmitter, a photoelectric cell,a scanning device having a plurality of peripheral areas, one for eachsymbol, each having elemental control areas corresponding to the lightand dark areas of a so symbol, a light port for each peripheral area, aplurality of permutation members selectively positionable in codecombinations to select one of said ports to admit light onto saidphotoelectric cell, and means to generate signals according to theactivation of the photoelectric cell.

II). In a photoelectric transmitter adapted to transmit facsimilesignals comprising a scanning device having a plurality of areas, eacharea ter comprising a plurality ofapertured plateshaving for eachpermuted setting an opening corresponding to each area; and means togenerate signals according to the activation of the photoelectric cell.11. In a photoelectric transmitter adapted to transmit facsimile signalscomprising a scanning device having a plurality of peripheral areas, onefor eaclil symbol, each having elemental control areas corresponding tothe light and dark areas of a scanned symbol, a sourceof light, aphotoelectric cell, a light shutter comprising a plurality of aperturedplates having for each permuted setting thereof an opening correspondingto each peripheral area whereby light is admitted from said source ontosaid photoelectric cell, and means to generate facsimile signalsaccording to the activation of said photoelectric cell. 12. Incombination, a telegraph transmitter,

means for radiating light, light sensitive means in the path of saidlight, a scanning device located between said light radiating means andsaid light sensitive means for interrupting said light, said devicehaving a plurality of peripheral areas, one for each symbol, each havingelemental control areas corresponding to the light and dark areas of ascanned symbol, a light shutter comprising a plurality of aperturedplates having for each permuted setting thereof an opening correspondingto each peripheral area whereby light is admitted from said firstrecited means onto said light sensitive means, and means to generatesignals according to the activation of said light sensitive means.

13. In a facsimile printing telegraph transmitter, a photoelectric cell,a scanning device having a plurality of peripheral areas, one for eachsymbol, each having elemental control areas corresponding to the lightand dark areas of a scanned symbol, a light port for each peripheralarea, a plurality of transparent light-carrying rods, one extending fromeach port to said photoelectric cell, a plurality of permutation membersselectively positionable in code combinations to select one of saidports to admit, through the associated rod, light onto saidphotoelectric cell, i

arranged according to the character represented,

means for producing a concentrated beam of light, means for reflectingsaid beam of light,

' a photoelectric cell, a light shutter comprising a plurality ofapertured plates having for each permuted setting an openingcorresponding to each area, a plurality, of light-carrying rods, oneextending from each opening to said photoelectric cell, for carryingsaid light from said reflecting means to said photoelectric cell, andmeans to generate signals according to the activation of thephotoelectric cell.

15. In a photoelectric transmitter, a constantly moving scanning device,an intermittently operating sensing device, and means to synchronize theintermittent operations of the sensing device with the motion of thescanning device.

16. In a photoelectric transmitter, means to produce a beam of radiantenergy, a plurality of scanning elements, a photoelectric cell,radiation deflecting means individual to each scanning element, means tomove any deflecting means into the path of the beam to deflect radiantenergy onto its corresponding scanning element to determine theinformation to be transmitted, means to project the radiant energypassing the scanning means onto the sensitive element of thephotoelectric cell, and means to generate information-carrying signalsaccording to the activation of the photoelectric cell.

17. In a photoelectric transmitter, a source of illumination, aphotoelectric cell, a screen containing striations corresponding to aspecific character and, each striation comprising a series oftransparent and opaque portions representing signal impulses to betransmitted, and means to pass said screen between said source and saidcell so as to cause said signal representations to activate said cell.

18. In a photoelectric transmitter, a source of light, a photoelectriccell, a screen containing striations, each striation corresponding to aspecific character and comprising a series of transparent and opaqueportions representing signal impulses to be transmitted, means to passsaid screen between said source and said cell, and means to select astriation to cause the signal representation thereon to activate saidcell.

19. In a photoelectric transmitter, a source of light, a photoelectriccell, a screen containing striations, each striation corresponding to aspecific character and comprising a series of transparent and opaqueportions representing signal impulses to be transmitted, means to passsaid screen between said source and said cell, and a permutation codemechanism operable to select a striation to cause the signalrepresentation thereon to activate said cell.

20. In a photoelectric transmitter, a source of light, a photoelectriccell, a screen containing striations, each striation comprising a seriesof transparent and opaque portions representing signal impulses to betransmitted, means to pass said screen between said source and saidcell, and a plurality' of apertured plates operable permutably to effectan alignment of apertures opposite any one of said striations to causethe signal representation on said striation to activate said cell.

21. In a photoelectric transmitter, a source of light, a photoelectriccell, a screen containing striations, each striation comprising a seriesof transparent and opaque portions representing signal impulses to betransmitted, means for constantly rotating said screen to pass itsperiphery between said source and said cell, a signal controllingmedium, intermittently operated means for controlling, through saidmedium, the signal to be transmitted, and means associated with saidfirst-mentioned means effective under the control of said medium togovern the operativeness of said intermittently operated means.

22. In a photoelectric transmitter, a source of light, a photoelectriccell, a screen containing striations, each striation comprising a seriesof transparent and opaque portions representing signal impulses to betransmitted, means to pass said screen between said source and saidcell, a plurality of light-carrying rods, one extending from eachstriation to said cell, and 'means to select a striation to enable thepassage of said light through the associated rod onto said cell to causethe signal representation on said striation to activate said cell.

23. In a keyboard photoelectric transmitter, a series of keys, a sourceof light, a photoelectric cell, a screen containing striationscorresponding to a specific character and, each striation comprising aseries of transparent and opaque portions representing signal impulsesto be transmitted, means to pass said screen between said source oflight'and said cell, and a shutter means associated with said keysnormally effective to prevent the impingement of said light upon saidcell, and effective upon operation of said keys to admit said light tocause the signal representation on a striation to activate said blocksof signals, and applying to the line in series with the direct currentan opposite potential of higher value produced by the rectified impulsesto form impulses of polar nature corresponding to said signals.

25. In a photoelectric transmitter, an area assigned to each of. aplurality of signals to be transmitted, means to illuminate each areawhen a corresponding signal is to be transmitted, a singlephoto-sensitive device, a light conducting rod leading from each area tothe photo-sensitive device, and means controlled by the photo-sensitivedevice to generate signals according to the light transmitted throughthe rods.

26. In a photoelectric transmitter, a constantly rotating scanningcylinder, a plurality of arrangements of opaque and transparent lightadmitting areas in said cylinder, a source of light, a photo-sensitivedevice, means to select one of the plurality of arrangements at a timeto control the impingement of the light from the source on thephoto-sensitive device, and means associated with said selecting meansand eifective automatically between signalling intervals to cut ofi thelight from all areas.

27. The method of generating polar signals for telegraphic transmission,which comprises the steps of supplying one polarity of potentialcontinuously from a direct current source to the circuit, generatingblocks of impulses according to signals to be transmitted, transformingsaid blocks of impulses into alternating current, rectifying saidtransformed blocks of signals, and applying to the same circuit inseries with the direct current an opposite potential of higher valueproduced by the rectified impulses to form impulses of polar naturecorresponding to said signals.

28. In a keyboard facsimile transmitter, a series of keys, aphotoelectric cell, means to activate said photoelectric cell, a screencontaining a plurality of groups of representations of signal aacaseavate said photoelectric cell, a scanning cylinder containing arepresentation of thesignal impulses to be transmitted formed as aseries of areas having difierent light controlling abilities, meanscontrolled by said keys for releasing said scanning cylinder for onerevolution only, and-a plurality of laminated shutter plates controlledby said keys effective when operated to cause said activating means toinfluence said photoelectric cell in accordance with one of said seriesof areas.

32. In a keyboard facsimile transmitter,a series of keys, aphotoelectric cell, means to activate said impulses to be transmitted,each group specific to a character and formed as a series of aperturedand unapertu'red portions, and means controlled by said keys wherebysaid screen is passed between said activating means and saidphotoelectric cell so as to cause said representation of the impulses toaffect said photoelectric cell.

29. In a keyboard facsimile transmitter, 21.

series of keys, a photoelectric cell, means to activate saidphotoelectric cell, a screen containing a plurality of groups ofrepresentations of signal impulses to be transmitted, each grouparranged according to a specific character and formed with portionshaving different light controlling. abilities, and means controlled bysaid keys whereby said screen is passed between said activating meansand said photoelectric cell so as to cause said representation of theimpulses to affect said photoelectric cell.

30. In a facsimile transmitter, a photoelectric cell, a scanning devicehaving a plurality of areas,

each area corresponding to a character and having portions withdifl'erent light controlling abilities arranged according to thecharacter represented, shutter mechanism, means to actuate saidmechanism to select an area according to the character to betransmitted, means to activate the photoelectric cell according to thelight controlling abilities of the different areas, and means togenerate signals according to the activation of the photelectric cell.

' 31'. In a keyboard facsimile transmitter, a sephotoelectric cell,ascanning cylinder containing a representation of the signal impulses tobe transmitted formed as a series of areas having diflerent lightcontrolling abilities, a plurality of laminated plates apertured inaccordance with a permutation code, and means controlled by said keysfor operating said plates permutably to cause said activating means toinfluence said photoelectric cell in accordance with the key operated.

33. In a photoelectric transmitter, a character member having areas ofdifferent light controlling abilities arranged in lines, a single linefor each character, a photoelectric cell, means to select one of thelines on the character member, and means to activate the photoelectriccell for the duration of a signal interval according to the operation ofsaid selecting means. 7

34. In a photoelectric transmitter, a character member havingareas ofdifferent light controlling abilities arranged in lines, asingle linefor each character, a photoelectric cell, shutter mechanism to selectone of the lines on the character member, and means to activate thephotoelectric cell for the duration of a signal interval according tothe operation of said shutter mechanism.

35. In a photoelectric transmitter, a character member having areas ofdifferent light controlling abilities arranged in lines, a single linefor each character, a photoelectric cell, activating means therefor, aplurality of laminated plates pulses to be transmitted formed as aseries of groups of transparentor opaque portions, means controlled bysaid keys for releasing said scanning cylinder for one revolution only,and shutter mechanism associated with said keys effective upon operationof said keys to cause said activating means to influence saidphotoelectric cell in accordance with one of said groups of transparentand opaque portions.

37. In a keyboard facsimile transmitter, a plurality of key levers,selector bars arranged transversely of said key levers 'and controlledthereby, a scanning'cylinder disposed above and parallel to saidselector mechanism, said cylinder containing a representation of thesignal impulses to be transmitted formed as a series of groups oftransparent and opaque portions, a single photoelectric cell coextensivewith the series of representations on said cylinder, a single 7 means toactivate said photoelectric cell, means ries of keys, a photoelectriccell, means to acticontrolled by said keys for releasing said scanningcylinder for one revolution only, and a shutrow, a shutter mechanism tocontrol said portsto admit light onto said photoelectric cell, and meansto generate signals according to the activation of the photoelectriccell.

39. In a facsimile printing telegraph transmitter, a photoelectric cell,a scanning device having a plurality of peripheral areas, one for eachsymbol, each peripheral area having elemental control areascorresponding to the light and dark areas of a scanned symbol, a lightport for each peripheral area, a shutter mechanism comprising aplurality of laminated plates apertured according to a permutation codeand having for each permuted setting an alignment of aperturescorresponding to each peripheral area, and means to generate signalsaccording to the activation of the photoelectric cell.

40. In combination, a telegraph transmitter, means for radiating light,light sensitive means in the path of said light, a scanning cylinder 10-cai'ed between said light radiating means and said light sensitive meansfor interrupting said light, said cylinder having a plurality ofperipheral rows, one for each symbol, each row having elemental controlareas corresponding to the light and dark areas of a scanned symbol,shutter mechanism corresponding to said peripheral rows whereby light isadmitted from saidfirst recited means onto said light sensitive means,and means to generate signals according to the activation of said lightsensitive means.

41. In a facsimile transmitter, a photoelectric cell, a scanning devicehaving a plurality of areas, each area corresponding to a characterandhaving portions with diflerent light controlling abilities arrangedaccording to the character represented, means to select an areaaccording to the character to be transmitted, a plurality oflightcarrying rods, one extending from each area to said photoelectriccell, means eifective through said light-carrying rods to activate thephotoelectric cell according to the light controlling abilities of thediflerent areas, and means to generate signals according to theactivation of the photoelectric cell.

42. In a facsimile printing telegraph transmitter, a photoelectric cell,a scanning cylinder having a plurality of peripheral rows, one for eachsymbol, each row having elemental control areas corresponding to thelight and dark areas of a scanned symbol, a light port for eachperipheral row, a plurality of light-carrying rods contained within thescanning cylinder and each conformed so as to present one end thereoftoward a light port and the opposite end thereof toward thephotoelectric cell, means effective through said light-carrying rods toactivate the photoelectric cell according to the light control-' lingabilities of the different areas, and means to generate signalsaccording to the activation of the photoelectric cell;

43. In a photoelectric transmitter, a constantly rotating scanningcylinder, a step-by-step tape sensing device, and means to synchronizethe 7 stepping of the sensing device with the motion of the scanningcylinder.

44. In a photoelectric transmitter, a constantly rotating scanningcylinder, a step-by-step tape sensing device, and cam means tosynchronize the stepping of the sensing device with the motion of thescanning cylinder. 7

45. In a photoelectric transmitter, a constantly moving scanning device,a cam means associated with said scanning device, an intermittently op,

erating sensing device, and means associated with said sensing deviceand cooperable with said cam means to synchronize the intermittentoperations of the sensing device with the motion of the scanning device.

46. In a photoelectric transmitter, a constantly moving scanning devicehaving a plurality of areas, means to select an area according to thecharacter to be transmitter, an intermittently operated sensing devicefor controlling the operation of said means, and means to synchronizethe intermittent operations of the sensing'device with the motion of thescanning device.

47. In a photoelectric transmitter, a photoelectric cell, a constantlymoving scanning device having a plurality of areas, each areacorresponding to a character and having portions with diiferent lightcontrolling abilities arranged according to the character represented,means to select an area according to the character to be transmitted, anintermittently operated sensing device for controlling the operation ofsaid selecting means, means to synchronize the intermittent operationsof the sensing device with the motion of the scanning device, means toactivate the photoelectric cell according to the light controllingabilities of the different areas, and means to generate signalsaccording to the activation of the photoelectric cell.

48. In a keyboard photoelectric transmitter, a series oi keys, a sourceof light, a photoelectric cell, a screen containing striations, eachstriation comprising a series of transparent and opaque portionsrepresenting signal impulses to be transmitted, means to pass saidscreen in a continuous movement between said source of light and saidcell, and shutter mechanism eifective upon operation (if said keys toadmit said light to cause the signal representation on a striation toactivate said cell.

49. In a facsimile transmitter, a photoelectric cell, a scanning devicehaving a plurality of rows of signal controlling areas, each rowspecific to a character and having areas with difierent lightcontrolling abilities arranged according to the character represented,means to select a row according to the character to be transmitted,means to activate the photoelectric cell according to the lightcontrolling abilities of the diflerent areas, and means to generatesignals according to the activation of the photoelectric cell.

50. In a photoelectric transmitter, a constantly moving scanning device,an intermittently operating sensing device for controlling theeflectiveness of said scanning device, and means to symchronize theintermittent operations of the sensing device with the motion of thescanning device.

51. In a photoelectric transmitter, a constantly rotating scanningcylinder, a plurality of arrangements of gpaque and transparent lightcontrolling areas in said cylinder, a source of light, a photo-sensitivedevice, a plurality of apertured bars operable permutably to select oneof the plurality of arrangements to control the impinge- 52. The methodof generating polar signals for' the graphic transmission, whichcomprises the steps of supplying one polarity of potential continuouslyfrom a direct current source to the circuit, generating intervals ofcurrent-no-current signals, transforming said signals into alternatingcurrent intervals, rectifying said alternating current, and applying tothe same circuit in series with the direct current an opposite potentialof higher value produced by the rectified current to form impulses ofpolar nature corresponding to said signals.

53. In a facsimile transmitter, a photoelectric cell, a scanning devicehaving a plurality of areas, each area corresponding to a character andhaving portions with variant light controlling abilities arrangedaccording to the character represented, means to select an .areaaccording to the character to be transmitted, means to activate thephotoelectric'cell according to the light controlling abilities of thedifferent areas, and

means to generate signals according to the activation of thephotoelectric cell.

54. In a signal transmitting system, a photoelectric cell, means toilluminate the photoelectric cell for varying intervals according to thesignals to be transmitted, means to interrupt the illumination aplurality of times during each interval, means to generate blocks ofalternating current impulses corresponding to the-illumination of thecell, a signaling circuit, means to apply direct current potential ofone polarity to the line, means to rectify the blocks of alternatingcurrent, and means to apply the potential of higher value resulting fromthe rectified current to the signaling circuit to oppose the directcurrent potential to produce polar signals corresponding to theillumination of the photoelectric cell.

LOUIS M. POTTS.

